Generally, a navigation system is a system which provides information for driving of a transportation device such as a vehicle by using an artificial satellite. The navigation system is automatic.
A typical navigation system is configured into one terminal and includes a storage medium to store map data. Also, the navigation system includes a Global Positioning System (GPS) receiver to receive GPS signals.
The navigation system calculates a location of a vehicle, informs a user of a current location of the vehicle based on the calculated location of the vehicle. Also, the navigation system routes an optimal path from the current location to the user's desired destination and guides the user to the desired location, providing the user with various types of associated information along the path.
A method of calculating a location of a vehicle receives location data from a GPS satellite using a GPS receiver, and calculates the current location of the vehicle based on the received location data.
Another method of calculating a location of a vehicle calculates the current location of the vehicle using a gyro sensor and an acceleration sensor, which are installed in the vehicle. In this instance, the other method receives GPS signals, calculates the current location of the vehicle based on the received GPS signals, and corrects the calculated current location based on results detected by the gyro sensor and the acceleration sensor.
An at least two-axis acceleration sensor is included to determine whether the vehicle is turning left or right. In this instance, it is possible to completely match one axis of the two axes of the acceleration sensor with a driving direction of the vehicle and match another axis of the acceleration sensor with a left/right direction of the vehicle, and thereby read only a value of a sensor corresponding to the left/right axis and determine a turning direction of the vehicle.
In the case of the method of determining the turning direction, when an installation method in a vehicle is not fixed such as a portable navigation device (PND), it is difficult to accurately install the PND by matching axes of a sensor with the driving direction of the vehicle and the left/right direction of the vehicle respectively. Also, when the user is required to accurately install the PND for the accurate operation, it may create some burdens for the user.
If a navigation device is not accurately installed, it may be determined the vehicle is turning even though the vehicle is in a straight-driving state. Also, it may be determined the vehicle is not turning even though the vehicle is in a turning state. Specifically, accurate determination may not be performed.
Specifically, in the above method, when only one axis of a sensor matching the left/right direction is used, for example, when a sensor value of a corresponding axis has a positive value, it is determined the vehicle is in a right-turning state. Conversely, when the sensor value has a negative value, it is determined the vehicle is in a left-turning state. Specifically, since a comparatively radical method is used, the installation method in the vehicle may be significantly affected. Also, data obtained from the sensor may be inaccurate.